This invention relates to DC power controllers and, more particularly, to current limited DC power controllers.
High voltage DC power systems for advanced aircraft and spacecraft require current limiting power controllers to protect the power source, loads and wiring. During a short circuit, full line voltage appears across the switch element of a power controller while it is limiting current to a safe value. Circuit techniques suitable for low voltage DC systems, such as 28 volts DC, are not satisfactory at higher voltages such as 150 or 200 volts DC. At the higher levels, transistor safe operating area curves are severely limited. A large transistor capable of carrying 150 amperes DC continuously with a forward voltage drop of one volt DC may be capable of supporting 150 volts DC at the same current level for only 100 microseconds. Under such operating criteria, current limiting control must be fast and accurate to prevent destruction of the switch element.
Advanced electrical power systems also require power controllers with programmable ratings. Programmable power controllers reduce inventory costs and allow reconfiguration of the electrical system to support different missions, to conform to limitations in power sources, and to operate under damage conditions.